import java.util.LinkedList;
import java.util.Queue;

/**
 * Implement the following operations of a stack using queues.
 * <p>
 * push(x) -- Push element x onto stack.
 * pop() -- Removes the element on top of the stack.
 * top() -- Get the top element.
 * empty() -- Return whether the stack is empty.
 * <p>
 * Notes:
 * You must use only standard operations of a queue -- which means only push to back, peek/pop from front, size, and is empty operations are valid.
 * Depending on your language, queue may not be supported natively. You may simulate a queue by using a list or deque (double-ended queue), as long as you use only standard operations of a queue.
 * You may assume that all operations are valid (for example, no pop or top operations will be called on an empty stack).
 * <p>
 * Credits:
 * Special thanks to @jianchao.li.fighter for adding this problem and all test cases.
 * <p>
 * Created by drfish on 6/8/2017.
 */
public class _225ImplementStackUsingQueues {
    public class MyStack {
        private Queue<Integer> queue;

        /**
         * Initialize your data structure here.
         */
        public MyStack() {
            queue = new LinkedList<>();
        }

        /**
         * Push element x onto stack.
         */
        public void push(int x) {
            queue.add(x);
            for (int i = 0; i < queue.size() - 1; i++) {
                queue.add(queue.poll());
            }
        }

        /**
         * Removes the element on top of the stack and returns that element.
         */
        public int pop() {
            return queue.poll();
        }

        /**
         * Get the top element.
         */
        public int top() {
            return queue.peek();
        }

        /**
         * Returns whether the stack is empty.
         */
        public boolean empty() {
            return queue.isEmpty();
        }
    }
}
